Diabetic Retinopathy: Basic Information

Why is it important to know how diabetes affects the eyes?

If you are among the 10 million people in the United States who have diabetes - or if someone close to you has this disease - you should know that diabetes can affect the eyes and cause visual impairment.

Fortunately, there are ways to prevent or lessen the eye damage caused by diabetes. That is why it is so important for people with this disease to have a professional eye examination as soon as their diabetes is diagnosed, and at least once a year thereafter.

Regular eye examinations are especially important for people who have had diabetes 5 years or longer, for those who have difficulty controlling the level of sugar in their blood, and for diabetic women who are pregnant. All of these people are at increased risk for diabetes-associated eye problems.

What is diabetic retinopathy?

Diabetic retinopathy is a potentially serious eye disease caused by diabetes. It affects the retina - the light-sensitive tissue at the back of the eye that transmits visual messages to the brain. Damage to this delicate tissue may result in visual impairment or blindness.

Diabetic retinopathy begins with a slight deterioration in the small blood vessels of the retina. Portions of the vessel walls balloon outward and fluid starts to leak from the vessels into the surrounding retinal tissue. Generally, these initial changes in the retina cause no visual symptoms. However, they can be detected by an eye specialist who is trained to recognize subtle signs of retinal disease.

In many people with diabetic retinopathy, the disease remains mild and never causes visual problems. But in some individuals, continued leakage from the retinal blood vessels leads to macular edema. This is a build-up of fluid in the macula - the part of the retina responsible for the sharp, clear vision used in reading and driving. When critical areas of the macula become swollen with excess fluid, vision may be so badly blurred that these activities become difficult or impossible.

Some people with diabetes develop an even more sight-threatening condition called proliferative retinopathy. It may occur in people who have macular edema, but also can develop in those who don't. In proliferative retinopathy, abnormal new blood vessels grow on the surface of the retina. These fragile new vessels can easily rupture and bleed into the middle of the eye, blocking vision. Scar tissue also may form near the retina, ultimately detaching it from the back of the eye. Severe visual loss, even permanent blindness, may result. But this happens in only a small minority of people with diabetes.

How many diabetics are affected?

Approximately 40 percent of all people with diabetes have at least mild signs of diabetic retinopathy. About 3 percent have suffered severe visual loss because of this disease.

In general, the longer one has had diabetes, the greater one's chances of developing diabetic retinopathy.

What are the symptoms of diabetic retinopathy?

As already indicated, diabetic retinopathy generally causes no symptoms in its earliest stages. For the person who develops macular edema, blurring of vision may provide a clue that something is wrong. But proliferative retinopathy can progress a long way without any warning signs. That is why a person with diabetes should make regular visits to an eye specialist, so any eye problems can be detected and treated if necessary.